Securing means for the screwthreaded bases of electric current leads



Jan. 10, 1939. J KRGS 2,143,562 SECURING MEANS FOR THE SCREW-THREADED BASES OF ELECTRIC CURRENT LEADS Filed Sept. l4, 1936 .70 van for:

Patented Jan. 10, 1939 PATENT OFFICE SECURING MEANS FOR THE SCREW- THREADED BASES 0F ELECTRIC CUR- RENT LEADS Josef Kriis, Frankfort-on-the-Main, Germany Application September 14, 1936, Serial No. 100,626

- 5 Claims.

Electric lamp securing devices are already known for the purpose of preventing removal of the lamp. They act with the aid of catches which permit the lamp to be screwed in but become operative when an attempt is made to screw out the lamp and thus make it impossible to screw out the lamp without use of an implement designed for the particular purpose or destruction of the securing device. I

This invention consists in a means for securing the screw-threaded bases of electric current connections of all kinds against unintended movement in order to thereby maintain a uniform conduction of current in spite of shakings of the connections. When situated. on vehicles and machines or in work shops or employed when carrying out rough work or in hand lamps and so forth, the screw-threaded bases are often subjected to considerable shakings which cause a slackening of the base and thus disturb the steady supply of current. If for example an electric lamp is in a protective casing it is necessary not only to provide for its securement but also for its ready replacement.

The subject of the said invention is to entirely exclude an unintended loosening of the screw-threaded base even if subjected to strong vibrations and at the same time in no way prevent the removal of the lamp or other article.

This object is attained by arranging the securing means resilient and rockable, whereby by overcoming a predetermined resistance, the screw-threaded base can be easily screwed in and out, but nevertheless a slackening of the electric contact due to vibrations or the like is made impossible. The securing means itself may have inherent resilient properties or be mounted in a resilient manner in order to rock at each unintended alterations in the direction of turning of the screw-threaded base, toofier a resistance before rocking, and after rocking in the desired direction of rotation, to offer no further resistance to rotation of the screw-threaded base. The securing means can act on any part of the screw-threaded base and can be easily provided on the holders or casings of electric current connections.

Various constructional examples of the invention are shown in the accompanying drawing, in

which-- Figure l is a plan view of a securing means with a resilient wire.

Figure 2 is a plan view of a securing means with a resilient mounting of the securing wire.

Figure 3 is a plan view showing a securing pin bent at the end.

Figure 4 is a view in longitudinal section through a lamp holder with resilient carrying means for the securing pin.

Figure 5 is a section on aline corresponding with the line AB of Figure 4.

Figure 6 is a side view of a securing meanswith helical spring.

Figure 7 is a section on line C-D of Figure 6.

Figure 8 is a front view of a securing means with conically wound spring.

Referring to the drawing, the securing means according. to Figural is shown in connection with a screw-threaded base a which is shown in section and is screwed into a screw-threaded socket I) provided with a slot c. Generally the screw-threaded base a is provided with a screwthreaded metallic shell which forms the outer surface of the base. The shell is however not indicated in the drawing. Furthermore the electrical connections are also not shown. The whole screw-threaded base is, shown hatched. A resilient pin e rests on the holder (2 and projects through the slot 6 of the :said socket and lies against the screw-thread of the screw-threaded base.

If the screw-threaded base a is rotated in the direction shown by the arrow, the elastic pin e is moved with it and rocks from the position I to the position II. The mid-position, in which the pin has to bend, is indicated in dot-and-dash lines. When the pin has rocked into the position II it offers no further resistance to continuation of rotation of the screw-threaded base in the direction of the arrow. There however immediately occurs a resistance to rotation of the screw-threaded base in the reverse direction to the arrow, and therefore the screw-threaded base is secured in all positions by the resilient pin against rotating in a direction contrary to that in which the pin points. The pin mounting d must be rotatable in order that in all its positions, the pin shall lie against the screw-threaded base.

When the screw-threaded base is screwed home into the position of contact; the pin therefor-e gives complete security against undesired slackening of the screw connection under the action of vibrations, shaking movements and the like, whereby a uniform and complete contact is lastingly ensured. V

In the construction according to Figure 2, the pin mounting d is mounted in a resilient manner and the pin I may be stiff. When the screw.

threaded base a is turned in the direction of the arrow the pin f is rocked from the position I into the position II, the mounting being thereby pushed from the position I into the position II and then pushed back into the position I as the pin rocks into the position II. In this construction of securing means the operation is the same' as that described with reference to the construction shown in Figure 1. In this construction also the pin must press against the screwthreaded base in both of the end positions of the pin.

Figure 3 shows a. securing pin g which has a bent end h. This bending serves to increase the resilient securing efiect. The securing pin is shown in the mid-position during rotation of the screw spigot and is rocked into one or other of the end positions I and II on continued rotation of the screw-threaded base, according to the direction of rotation of the said screwthreaded base.

In the construction according to Figures 4 and 5, there is, in addition to the socket l which serves to receive the screw-threaded base of an electric lamp, plug connection or the like, a housing 3 containing a space 2 in which a helical steel wire l is placed. This steel wire 4 is held fast in a lateral lug 5 of the screw-threaded socket l and is provided with a laterally projecting end 6 which extends through a slot 'l' in the screw-threaded socket and presses resiliently against the screw-threaded base 8. The steel wire is thickest at the end by which it is held fast and its cross-section decreases in the direction of its laterally projecting end.

From the cross-section shown in Figure 5 it can be seen how the end 6 rests resiliently against the screw-threaded base and rocked over by the screw-threaded base into the position shown in dot-and-dash lines when the screwthreaded base is screwed into the socket, the resilient wire being pressed away from the screw threaded base during the rocking movement until the end 6 is reaching its second end position. The end 6 presses against the metallic shell 9 of the screw-threaded base 8 and secures it against unintended rotation. When the screw-threaded base is unscrewed from the socket l by the exercise of a small amount of force the end 6 is rocked over into the position shown in full lines and then ofiers no further resistance to the further screwing-out of the screw-threaded base. The conductors serving to supply the electric current have been omitted from the drawing because they are of the known kind and can be arranged in known manner.

In the construction shown in Figures 6 and '7, the securing means is in the form of a helical spring l0 mounted on a guide post II which is held in brackets 52 and i3 on the socket M. The straight upper end E5 of the helical spring I!) extends horizontally through the slot 16 provided in the socket l4 into the interior of the said socket, and the straight lower end ll of the helical spring ii] rests against the exterior of the socket l4. Both brackets 12 and [3 are formed by portions pressed out of the socket M, and the portion for the bracket l2 is so pressed out that the slot in the socket for accommodation of the end l5 of the helical spring i0 is simultaneously formed by the same operation. The slot may alternatively be at a lower elevation and the bracket 12 be arranged in a bentover part of the rim of the screw-threaded socket or lamp holder.

The helical spring '8 according to construction shown in Figure 8 is provided with a conical widening l9 towards the place where the securement takes place, whereby the resilient effect of the rocking pin 20 is increased. The lower, cylindrical part of the spring can surround the guide post more closely and thereby obtain better guidance.

An important advantage of the invention lies also in the safety given by its employment in the case of installations where there is danger of fire, because the production of a spark which occurs when a screw-threaded base forming a contact becomes slack can no longer take place.

The simplicity and certainty of action of securing means according to the invention lies in the reversible effect of the said means which is constantly ready for action in all cases, can be embodiedin the most diverse constructions of the most diverse dimensional proportions and can be suited to the inaccuracies in manufacture of such electrical articles in order to contribute to a constantly perfect securement.

It is exactly in the absolute reliability of the securing means in combination with the simplicity of construction that the technical value of the invention lies.

I claim:

1. In a socket for the screw-threaded base of electric lamps, connecting plugs and the like, the combination with a screw shell provided with an aperture in its wall, of locking means comprising a rockable member, one end portion of which extends from a support located exteriorly of said screw shell and radially spaced therefrom through said aperture and into engagement with the screw-threaded base inserted in said screw shell, said end portion of said rockable member extending somewhat less than tangentially to the circumference of the screw-threaded base and in a direction to normally resist an accidental rotation of said base in a direction opposite to that the screw-threaded base engaging end of said rockable member points, said rockable member, upon said resistance having been overcome, being rocked into another position in which its base engaging end portion engages said base also somewhat less than tangentially, but in a direction in which it no longer ofiers a resistance against further rotation of the threaded base in the same direction, but will resist rotation in the opposite direction.

2. In a socket for the screw-threaded base of electric lamps, connecting plugs and the like, the combination with a screw shell provided with an aperture in its wall, of locking means comprising a pin of resilient material one end of which is fixed to a support located exteriorly of said screw shell and radially spaced therefrom, the other end of said pen extending through said aperture and into engagement with the screw-threaded base inserted in said screw shell, said last named end of said pin extending somewhat less than tangentially to. the circumference of the screw threaded base and in a direction to normally resist an accidental rotation of said base in a direction opposite to that the screw threaded base engaging end of said pin points, said pin, upon said resistance having been overcome, being rocked into another position in which its base engaging end engages said base also somewhat less than tangentially, but in a direction in which it no longer oifers a resistance against further rotation of the threaded base in the same direction ,but will resist rotation in the opposite direction.

8. In a socket for the screw-threaded base of electric lamps, connecting plugs and the like, the combination with a screw shell provided with an aperture in its wall, of locking means comprising a helical spring mounted exteriorly of said screw shell and parallel to the axis thereof, one end of said helical spring, being anchored fixedly with respect to said screw shell, the other end of said spring being extended laterally and projecting through said aperture and obliquely into engagement with the screw-threaded base inserted in said screw shell, said helical spring normally presenting a resistance against rotation of the screw-threaded base in a direction opposite to the direction in which the screw-threaded base engaging end of said spring points, said spring, upon said resistance having been overcome, being rocked into a position in which it no longer offers a resistance against further rotation of the threaded base in the same direction, but will resist rotation in the opposite direction.

4. In a socket for the screw-threaded base of electric lamps, connecting plugs and the like, the combination with a screw shell provided with an aperture in its wall, of locking means comprising a helical spring mounted exteriorly of said screw shell on a guide rod arranged parallel to the axis of the screw shell and mounted with its ends in brackets stamped outwardly from the body of said screw shell, one end of said helical spring being anchored fixedly with respect to said screw shell, the other end of said spring being extended laterally and projecting through said aperture and obliquely into engagement with the screw threaded base inserted in said screw shell, said helical spring normally presenting a resistance against rotation of the screw-threaded base in a direction opposite to the direction in which the screw-threaded base engaging end of said spring points, said spring, upon said resistance having been overcome, being rocked into a position in which it no longer offers a resistance against further rotation of the threaded base in the same direction, but will resist rotation in the opposite direction.

5. In a socket for the screw-threaded base of electric lamps, connecting plugs and the like, the combination with a screw shell provided with an aperture in its wall, of locking means comprising a conically wound helical spring, a guide post on the outside of said screw shell and spaced therefrom, said spring being mounted on said guide post, the lower end of said spring being wound cylindrically and closely surrounding the lower end of said guide post, the upper end of said spring being extended laterally and projecting through said aperture and obliquely into engagement with the screw-threaded base inserted in said screw shell, said spring normally presenting a resistance against rotation of the screwthreaded base in a direction opposite to the direction in which the'screw-threaded base engaging end of said spring points, said spring, upon said resistance having been overcome, being rocked into a position in which it no longer offers a resistance against further rotation of the threaded base in the same direction, but will resist rotation in the opposite direction.

JOSEF lines. 

